This invention relates generally to television signal transmission methods systems and specifically to a novel television signal transmission method and system which have improved co-channel performance characteristics.
A longstanding problem of television signal reception is that of minimizing interference from other transmitted signals. This has necessitated the controlled allocation of carrier signal frequencies and power ratings for transmitters as well as the locations of transmitting antennas. Interference problems can be readily classified as those due to adjacent channel signals, that is, television signals that are near the frequency of the signal being received and co-channel signal problems, that is, signals that are at the same frequency as the signal being received. In the first two of the above mentioned co-pending applications, various techniques are discussed for minimizing interference at a receiver from different television signals in both co-channel and adjacent channel situations. In particular, the role of dispersal filtering to reduce peak signal amplitudes and thereby reduce the interfering effects of such signals is described. The third mentioned application is concerned with the use of dispersal filtering for transmitting and accurately recovering a clock signal.
The present invention is directed to a method and system for significantly reducing co-channel interference by the use of directionally controllable dispersal filters in the transmitter and the receiver.